AIM-HIGH is a multicenter controlled clinical trial designed to test whether the drug combination extended release niacin plus simvastatin is superior to simvastatin alone, at comparable levels of in-treatment LDLcholesterol (LDL-C), for delaying the time to a first major cardiovascular (CV) disease outcome over a 4-year median follow-up in patients with atherogenic dyslipidemia. Prior clinical trials have found only 25-35% CV risk reduction using statin monotherapy (i.e., event rate 2/3 to 3/4 of placebo rate). The proposed study is needed to confirm whether statin-niacin combination therapy, designed to target a wider spectrum of dyslipidemic factors in addition to LDL-C, will provide a more substantial (>50%) reduction of CV events. Epidemiologic studies confirm the high prevalance of atherogenic dyslipidemia and its impact on CV event rates. Preliminary clinical trials suggest that targeting these factors with dylipidemic therapy will reduce CV events. The proposed study will enroll men and women >45 years old at high risk of recurrent CV events by virtue of having established CV disease together with the two dyslipidemic elements of metabolic syndrome - low HDL-cholesterol (HDL-C) [<=40 mg/dl] and high triglycerides (TG) [>=150 mg/dl]. The proposed study specifically aims to test this hypothesis for the primary composite clinical endpoint of CV death, nonfatal myocardial infarction (Ml), non-hemorrhagic stroke, or hospitalization for high-risk acute coronary syndrome with objective evidence of ischemia (troponin-positive or ST-segment deviation). A secondary endpoint is the composite of CV death, non-fatal Ml, or non-hemorrhagic stroke. The 3300-patient sample, to be recruited in 54 centers in US and Canada, will have >90% power for the primary endpoint, and up to 85% power to confirm a 29% risk reduction, relative to statin monotherapy, for the triple endpoint above. In summary, statins have little effect on HDL-C orTG, and only moderately reduce CV risk. AIM-HIGH is designed to confirm a substantially greater benefit from "complete" lipid therapy using statins plus niacin.